When 15 mph isn't enough

[flecc]

About cyclists' average speed - Most cyclists I see using bikes for commuting are doing 20-25mph.

Only the drop handlebar types, that's the sporting cyclists I mentioned. No-one sitting up with flat handlebars or higher is cycling continuously at 20 to 25 mph on the flat, and e-bikes are not drop handlebar bikes. That's why they are legislated for as other bikes, i.e. utility bikes.

Most UK ebikes being restricted from 20mph to 15mph. Well in my experience which is mainly with generic OEM type components manufactured in china. Most motors I've looked at are geared to spin at 20mph or faster with the wheel size and voltage that particular motor is marked up to use. I've researched 6 or 7 types of motor and found none set up to spin at 15mph let alone optimised for that top speed. As for the more expensive bikes, I was under the impression that most Ezees could be derestricted all though its a bit harder with the newer models. The vast majority of the plethora or cheaper bikes you will see use Suzhou Bafang motors and these are all geared to spin at 20mph for a particular wheel size and voltage. Restricting these to 15mph no load speed severely compromises the motor's performance in my experience and will provide very little assistance above 12mph. Tongxin are similar and the others I've come across have higher rpms.

This just is not true of e-bikes in the UK. As I've said the Wisper bikes use SB motors running to about 18 mph with a touch of restriction added to conform to 15 mph. eZee use voltage speed limiting on SB and other motors in their Quando and Sprint models, meaning the speed depends on the battery charge state, starting at 17/18 mph and declining to 15 mph.

The only eZee models that had readily removable restriction were the original Torq which used the Quando small wheel motor in a 28" wheel to give it up to 22 mph, and the F series and Torq 2 which have 20 mph motors for the US market. The original Torq is long discontinued and the other two have not been readily derestrictable more recently.

What size wheel the manufacturer specifies is irrelevant, so checking that is of little use for UK purposes. It's the rim size the e-bike manufacturer uses that matters, and in the bikes supplied to the UK, most are not wheeled to provide 20 mph or more on the road.

I've given specific models, but perhaps you can give these specific models that are wheeled to give 20 mph or more on the road if derestricted as you claim. As David Miall of Wisper has just said in another thread, the 200/250 Watt rated SB motors struggle to get to 20 mph even if geared for the USA, and that's been eZee's experience too, hence both manufacturers using higher rated 350 or 500 Watt motors specifically for the USA. The 250 Watt Torq 1 was deliberately very overgeared so it relied on torque as much as power to climb to it's high speed, for example, the original 22 mph Torq will free spin it's lifted wheel to well over 26 mph.

Other than eZee, the bulk of UK sales of reasonable quality e-bikes now are of the EU makes like Kalkhoff, Sparta and Gazelle, and from the far east, Giant, Powabyke, Wisper, Powacycle etc, none supplied as remotely capable of 20 mph by derestriction. Indeed the traditional Powabykes struggle a bit beyond 13 mph, and that's true of the Giant and Powacycle bikes as well, hence their widely reported lower average speeds.
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[Barnowl]

Just to respond to a few points people commented on.

About cyclists' average speed - Most cyclists I see using bikes for commuting are doing 20-25mph. Commuting makes up the vast majority of miles most people clock up in their lives imo. .

Hi Maestro. I suppose this all depends on where you ride but I always get a bit worried about perceptions of average speed. I use a cycle computer. Its not unusual for me cycle at 22 -27 MPH or even 30+ for short distances, given a suitable gradient. However using my bike to commute I find my average speed to be more like around 12MPH. That's easily explained by road junctions etc etc. Even at weekends with little traffic on the roads it's unusual for me to exceed an average of 14.5 MPH.
My perception is that I'm travelling much faster than most cyclists and I've only been overtaken once in the last 4 months. A big benefit for me with the electric bike, even with the legal limit, is accelerating back up to a reasonable speed quicky without breaking into a sweat.
I think you make some fair points and anything that encourages people to use their cars less is a good thing. Generally though I don't think the extra 4.5MPH assist would do much.

 

[flecc]

Hi Flecc

Airstream are selling for us in Canada and Tentcot have opened a new ebike division that will be launched in the spring.

Thanks David, now I'll know where to send inquirers. Unusual new diversion from caravans for Airstream!

I'll watch out for Tentcot's introduction. Any idea of where they will be locating the e-bike side?
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[Fecn]

To me, the problem isn't that 15.5mph assist is too slow.. That's fine for the assistance to cut off there. The problem is that many e-bikes seem to have their gearing designed to go no faster, or have significant drag when used without power. (Cytronex sounds like it breaks that mould). For all the times where I want assistance (i.e. going up great big 1-in-3 hills) then there's no way the bike's every going to go as fast as 15mph. For all the places where I can go faster than 15mph (i.e flats and downhill), then the assistance (for me at least) is pretty irrelevant anyway.

I changed the gearing on my Kalkhoff not because I wanted to be able to be a super-speedy lawbreaker, but because I wanted to pedal at a more sensible cadence on the many long gentle downhill slopes around here. I now have absolutely no idea where the Panasonic system stops helping out as I don't have a speedo fitted, but I'm certain it's more than 15.5mph (probably more like 25mph now)

So.. the question has to be now... How do I keep the cadence sane, but still have power assistance when I need it. I suspect the answer may involve either buying a different bike, or judicious use of a soldering iron.

 

[flecc]

So.. the question has to be now... How do I keep the cadence sane, but still have power assistance when I need it. I suspect the answer may involve either buying a different bike, or judicious use of a soldering iron.

It's Panasonic's drive through the chain system that is the problem, since it uses the cyclist's chain. If the gearing is set to limit the speed to 15 mph to suit the unit's low cadence system, that doesn't suit many cyclists. If altered for the cyclist, the limiting is breached.

There is no way to alter this at the motor or transmission, even with a soldering iron, the problem is fundamental. Hub motor systems like Cytonex don't have this problem since they don't use the cyclist's transmission.

The easiest way the Panasonic system could be altered is to have a motor cut out on the handlebar gear changer which operated on the top one or two gears. That way the motor would be limited to the lower gears, leaving the cyclist with one or two extra gears for their higher speed purposes. This would be easy for the manufacturer to implement, but Panasonic and Shimano would have to collaborate on the handlebar changer design.
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[Tiberius]

It makes my blood boil

Well, I suspect people would be surprised if I didn't join in this thread. After all, my daughter's nickname is Speedy, my son was Junior World Champion in a certain motorsport and I'm the man who took a homebuilt electric bike up the M5 at 120 mph.

But I think I just won't be drawn. Instead I want to publicly state my utmost respect for the law and its wisdom in all the forms it presents itself to us.

I am in Strasbourg all this week, discussing arcane points of European technical regulations.

At this point I think it is best to just cut away to a nice calming picture of the river outside the conference room....

Nick

 

[torrent99]

Well in my limited experience of e-biking (before my knees protested too much) I can say that for me in London, 15mph was quite enough. Yes there are occasions when I might want a little extra, but that was rare.

What is wanted is a bit more oomph getting to 15mph.
My Wisper (in common with most e-bikes I suspect) tails off the nearer it gets to 15mph.
More power is also required to tackle hills.

So if the controller is made so that it:
a) restricts max speed to the legal limit.
b) restricts accelleration to a "sensible" limit.
c) can detect when hills are slowing the bike down and provide more power/change internal motor gearing.

that'd suit me. YMMV. Of course this would require more sophisticated controllers, means of detecting bike speed etc.
(and with my knees the way they are, throttle only operation is essential)

Cheers

Steve

 

[flecc]

So if the controller is made so that it:
a) restricts max speed to the legal limit.
b) restricts accelleration to a "sensible" limit.
c) can detect when hills are slowing the bike down and provide more power/change internal motor gearing.

(and with my knees the way they are, throttle only operation is essential)

Your (a) is easy of course, but (b) is technically extremely difficult without adding much to the cost and complexity, so I'd rule it out as impractical. That leaves (c) which is also tricky either way.

The simplest way would be to allow the designer to provide a motor with ample power, say 500 Watt rated, about double the present, geared and limited for 15 mph, and that would climb no problem. The acceleration need not cause concern, since it would still have a lower power to weight ratio than any other powered vehicle, and the throttle you require would limit the power on demand.

These cannot happen of course, first since Europe and the UK will never agree to power increases, and second because we are shortly to comply with the EU "no throttle control only" rule.
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[Alex728]

where did the 15mph come from? was it simply picked out of a "eurochapeau" or was some research done to arrive at a "safe" figure?

 

[flecc]

where did the 15mph come from? was it simply picked out of a "eurochapeau" or was some research done to arrive at a "safe" figure?

We were about the first to legislate for e-bikes with a 200 Watts and a 12 mph limit, and this was based on typical utility cycling speeds. Regardless of what some seem to think, when much of the country cycled to work and used bikes for all sorts of other purposes, they rode at 10 to 12 mph, only sporty types with drop handlebars riding quicker. The whole purpose of e-bike legislation is to keep them as bicycles and not in any way motor vehicles.

Later the EU chose slightly higher limits for their more cycling oriented countries, 250 Watts and 25 kph (15.5 mph), so as we were gradually harmonising our laws with EU membership, we altered the UK speed limit to 15 mph.
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[The Maestro]

As David Miall of Wisper has just said in another thread, the 200/250 Watt rated SB motors struggle to get to 20 mph even if geared for the USA, and that's been eZee's experience too, .

Its not hard at all to make a SB motor go at that speed, if you buy a motor quoted as being for a 26" wheel, 36V battery and thats what you fit it to, it will spin at 19.5 - 20.5 mph (exact battery used and charge level make small differences). Same with 20" 36V. Those are the 2 I've tested but I'd stick my neck out looking at the specs of the other motors in the range and say that that is standard.

This is if you lift the wheel of the ground though. In practice the assistance is pretty much undetectable after 18 - 18.5 mph, even at 18 its much less than at 15. But for legal purposes what does the law mean? You could argue that if it spins at 20mph with the wheel lifted of the ground then thats the maximum assist speed even if the assistance is minimal.

Many (if not all ?) configurations reduce the assistance given sharply in the last 3-4 mph. I know there are technical reasons for this but I also seem to recall that the legislation mentions something about tailing off the power (might be wrong there). So anyway if we are talking about 15.5 mph we mayactually really talking about 12-13mph and if its 20 mph we are actually talking 18ish. Panasonic system bikes may be different.

Just about commuters - most commuters I see are on drop handle bikes however I think that this is just because they are the fastest kind of bike available so thats what commuters use. They aren't a safer type of bike and certainly don't have better brakes, grip or stability compared to mountain bikes or hybrids.

 

[flecc]

This is if you lift the wheel of the ground though. In practice the assistance is pretty much undetectable after 18 - 18.5 mph, even at 18 its much less than at 15. But for legal purposes what does the law mean?

That is what I mean, the law really only concerned with what the bike does in practice. As you say, battery voltage does make a difference to speed. For example, the Quando without limiting on it's SB motor will run to 17 or sometimes 18 mph if the battery is fresh off the charger, but that very quickly drops to 16 mph in a mile or so. Eventually as the battery empties it drops to 15 mph and shortly before the battery gives out, 14.5 mph.

Many (if not all ?) configurations reduce the assistance given sharply in the last 3-4 mph. I know there are technical reasons for this but I also seem to recall that the legislation mentions something about tailing off the power (might be wrong there). So anyway if we are talking about 15.5 mph we mayactually really talking about 12-13mph and if its 20 mph we are actually talking 18ish.

Unlimited bikes that are geared to run out of revs at 15 mph do roll off the power a bit as they pass their point of maximum efficiency at about 13 mph, and in that zone wind resistance is rising rapidly so acceleration rolls off anyway. EU law but not UK law requires the power to be rolled off as the bike approaches 25 kph/15.5 mph, but no roll off point or rate are specified, so it could mean anything and in practice does since it's widely ignored. This has no relationship to the 18/20 mph issue though, that being what a motor is capable of under driven conditions at those speeds against wind and rolling resistances.

Panasonic system bikes may be different.

I've given full details of the considerable differences in this article, describing how the strict Japanese law affects this unit.

Just about commuters - most commuters I see are on drop handle bikes however I think that this is just because they are the fastest kind of bike available so thats what commuters use. They aren't a safer type of bike and certainly don't have better brakes, grip or stability compared to mountain bikes or hybrids.

I completely agree.

The problem with legislation is that it's always out of date. As I described to Alex above, the e-bike speed limits were first set decades ago and relate to the normal cycling conditions at that time. There's been one increase from 12 mph to 15 mph a very long time ago which is what legislators would consider keeping up to date!

Since the law is always years behind the times, the very recent growth of fast cycle commuting in cities, as in London resulting from the congestion charge, has little chance of being taken into account for years yet. Add to that the fact that all roads legislation gets ever more strict, our chances of change are negligible. The only change currently scheduled is to the EU rule on pedelec only, no throttle only running, so more restriction.
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[torrent99]

Your (a) is easy of course, but (b) is technically extremely difficult without adding much to the cost and complexity, so I'd rule it out as impractical. That leaves (c) which is also tricky either way.

The simplest way would be to allow the designer to provide a motor with ample power, say 500 Watt rated, about double the present, geared and limited for 15 mph, and that would climb no problem. The acceleration need not cause concern, since it would still have a lower power to weight ratio than any other powered vehicle, and the throttle you require would limit the power on demand.
.

I don't see (b) as being that difficult. It's merely an electronic control issue, you monitor the change in speed and if the change is too great moderate the power applied. The controller does need to be more complex, indeed it needs to become "fly by wire" much like a modern car's ECU. However, it's unlikely to be beyond the capabilities of a cheap microcontroller.

Then as you say you put a sufficiently (over) powerful motor in and control that.

(c) Is really an extension of (b) if you have sufficient power. The control of (b) restricts the motor to a given acceleration curve, as the gradient/load increases (b) allows increased power up until the curve is exceeded. So a 500W motor is made to act like a 250W on the flat, but on the hills is allowed more free reign, making it still act as if it was a 250W motor on the flat.

The point here being if excessive power/acceleration is seen as a safety issue it can be electronically controlled.

Of course as you say, this is all moot with the current and future legislation....

 

[bogmonster]

Wow, this certainly has been a busy thread.....

Just picking up on a few points I have heard along the way:

Does, as somebody suggested, the motor really need to have a aticker on it stating the power? My TongXin does not. I know it is 180 watts and is well within the boundaries from a power perspective. I could print always label

Also, there are some commercial bikes that push the envelope a bit I think. Don't want to stir things up here but there are certainly bikes that assist up to about 16.5. How do these get away with this? My bike assists upto about 16.5 mph and I have considered putting a resistor in series with the throttle as I think this would make little difference to my commute time but would be closer to legal.

Cheers, BM

 

[flecc]

I don't see (b) as being that difficult. It's merely an electronic control issue, you monitor the change in speed and if the change is too great moderate the power applied. The controller does need to be more complex, indeed it needs to become "fly by wire" much like a modern car's ECU. However, it's unlikely to be beyond the capabilities of a cheap microcontroller.

I agree that approach will work, but given the simplicity of what we've got in hub motor controllers I couldn't see much willingness to implement it. Legislators have to take advice from the industry on tech matters, and the industry won't volunteer greater expense and would probably take my line.

As you've said and as David Miall of Wisper has just observed, we won't get any changes anyway, we're stuck with what we have, and with the prospect of even less shortly.

As much as anything, its the tiny size of the e-bike lobby that will ensure no ears are listening.
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[flecc]

Does, as somebody suggested, the motor really need to have a aticker on it stating the power? My TongXin does not. I know it is 180 watts and is well within the boundaries from a power perspective. I could print always label

Motors aren't labelled, I don't know where that idea comes in.

Also, there are some commercial bikes that push the envelope a bit I think. Don't want to stir things up here but there are certainly bikes that assist up to about 16.5. How do these get away with this? My bike assists upto about 16.5 mph and I have considered putting a resistor in series with the throttle as I think this would make little difference to my commute time but would be closer to legal.

This is for the various reasons I've described in my answers above, many bikes not having limiters and relying on gearing and battery voltage to limit the speed. My two bikes are like this. That's not a problem, roughly right is ok and no resistor is necessary.

 

[wotwozere]

Hi

15mph is plenty for me

thx

Bob

 

[MonVal Electra]

Wow, this certainly has been a busy thread.....

Just picking up on a few points I have heard along the way:

Does, as somebody suggested, the motor really need to have a sticker on it stating the power? My TongXin does not. I know it is 180 watts and is well within the boundaries from a power perspective. I could print always label

Also, there are some commercial bikes that push the envelope a bit I think. Don't want to stir things up here but there are certainly bikes that assist up to about 16.5. How do these get away with this? My bike assists upto about 16.5 mph and I have considered putting a resistor in series with the throttle as I think this would make little difference to my commute time but would be closer to legal.

Cheers, BM

Hello Bogmonster -
Please see the extract below taken from the CTC.org.uk website. ( when on their site, type EAPC in their search function and all that you see below will come up ).

The salient points to your questions have been highlighted, as too what plod can do.

______________________________________________________-
Electrically Assisted Pedal Cycle (EAPC)
More exacting requirements apply to the construction and use of bicycles and tricycles so defined by the Electrically Assisted Pedal Cycles Regulations.

Independent front and rear braking systems are required as initially described above, i.e. without exceptions and a fixed wheel does not count. These systems moreover, must perform to the level specified in BS6102/1:1981.

It is also illegal to use an EAPC on the road unless certain other systems are in efficient working order.

The pedals must be capable of propelling it.
The battery mustn't leak so as to be a source of danger.
The power switch or control must default to off, requiring a constant intervention from the rider in order to maintain power assistance.
The motor power output and the road speed at which it cuts out must not exceed the limits set out in the EAPC Regulations.
The EAPC must also be fitted with a plate (where you can easily read it) showing the manufacturer's name, the battery voltage and motor power output.
It is interesting to note that whereas these regulations cater for pedal cycles with any number of wheels from two (bicycle) to four (quadricycle) – or even more – electrical assistance is not permitted with more than three (tricycle). This means that load-carrying quadricycles, increasingly used for deliveries into areas from which motor vehicles are excluded, cannot receive a little necessary electrical assistance without themselves becoming classified as motor vehicles.

Enforcement
Any constable in uniform is empowered to stop a cyclist and test the cycle for compliance with these regulations, and to enter the premises where a cycle is kept if it has been involved in an accident up to 48 hours previously.

 

[Miles]

Pedal assist is allowed on four-wheeled vehicles under the EU directive, though.... so, for the present "pick 'n mix" situation........

 

[MonVal Electra]

Pedal assist is allowed on four-wheeled vehicles under the EU directive, though.... so, for the present "pick 'n mix" situation........

Correct, but as the UK won't ratify this directive, they are technically illegal in this country much to the chagrin of those of us using them. GRRRRRR!!!!